1. Field of the Invention
The present invention relates to a door handle module for a vehicle and an apparatus for locking and unlocking a vehicle door including the module, and more particularly, to a touch sensor-based door handle module for a vehicle and an apparatus for locking and unlocking a vehicle door including the module.
2. Discussion of Related Art
Generally, as a method in which locking and unlocking of a vehicle door are controlled, there are a method using a toggle switch and a method using a touch sensor. Among them, in a method using a touch sensor, locking and unlocking of a vehicle door may be controlled with only an action of approach (or contact) of a human body to a door handle.
FIG. 1 is a block diagram illustrating a conventional apparatus for controlling locking and unlocking of a vehicle door using a touch sensor.
Referring to FIG. 1, the conventional apparatus for controlling locking and unlocking of the vehicle includes a sensor 400 and a sensor controller 500 that controls the sensor 400.
The sensor 400 is embedded in a vehicle door handle and configured to detect a part of a human body that approaches the door handle, and may be a touch sensor, such as a capacitive sensor. That is, the capacitive sensor detects a capacitance changed when a part of a human body approaches.
The sensor controller 500 includes a charge condenser 501, a discharge condenser 502, a multiplexer (MUX) 503, a comparator 504, a controller 505, and a diode 506.
The charge condenser 501 discharges a capacitance which has been charged through a path including the sensor 400 and the discharge condenser 502.
The MUX 503 controls discharge of the charge condenser 501 in response to a discharge pulse signal from the controller 505.
The discharge condenser 502 discharges the charge condenser 501 through the MUX 503 in a no-load state.
The comparator 504 compares a reference voltage with a voltage that varies due to the discharge of the charge condenser 501 and outputs an effective pulse to the controller 505.
The controller 505 outputs the discharge pulse signal corresponding to the effective pulse input from the comparator 504 to the MUX 503. In addition, the controller 505 outputs a control signal to a door control apparatus.
In the conventional apparatus for locking and unlocking a vehicle door, when a part of a human body approaches the door handle, the sensor 400 detects a capacitance increased due to the approach of the part of the human body, the charge condenser 501 discharges through the MUX 503, the discharge condenser 502 and the sensor 400, and at this time, the comparator 504 compares the reference voltage with a voltage of the charge condenser 501 which is changed due to the discharge and outputs a comparison result to the controller 505.
The controller 505 calculates the number of effective pulses based on the comparison result input from the comparator 504. That is, the controller 505 compares the number of effective pulses, which is measured while the charge condenser 501 is being discharged, with the average number of pulses in a no-load state (or in a state in which the vehicle door is closed), and when a difference between the average number of pulses and the number of effective pulses occurs to be greater than or equal to the minimum number of effective pulses, determines that the change in capacitance is caused by the approach of the human body.
For example, when the average number of pulses in a no-load state is 500 and the number of effective pulses is changed to 450 due to an approach of a human body, the controller 505 computes 50 as a difference between the average number of effective pulses in the no-load state and the number of effective pulses due to the approach of the human body, and when the minimum number of effective pulses is less than 50, determines that the change in capacitance is due to the approach of the human body. If the difference is 2 to 3, it is a tolerance due to environmental factors, and is thus considered negligible.
Then, when the difference between the average number of effective pulses in a no-load state and the number of effective pulses due to an approach of a human body is determined to be greater than or equal to the minimum number of effective pulses that has been set beforehand, the controller 505 generates a door unlocked signal for changing a state of the vehicle door to a unlocked state and sends the generated unlocked signal to the door control apparatus. Then, in response to the door unlocked signal, the door control apparatus controls the vehicle door to be changed from a locked state to an unlocked state.
In the conventional apparatus for controlling locking and unlocking of the vehicle door, the controller 505 receives, as data from the comparator 504, the effective pulses generated while the sensor 400 is discharging electric charges due to an approach of a human body. At this time, the controller 505 recognizes data voltages Va, Vb, Vc, and Vd of the same voltage level that is generated in a falling section of each effective pulse, as shown in FIG. 2, and calculates the number of recognized data voltages as the number of effective pulses.
In this case, because the data voltages Va, Vb, Vc, and Vd detected in a falling section of the respective effective pulses drastically drop in a low voltage range of less than 1 V, the sensor 400 sensitively detects even a small change in capacitance, thereby causing a malfunction thereof. In particular, malfunctions frequently occur in an operating environment where a capacitance changes in a no-load state, for example, during rain.
In addition, although FIG. 2 illustrates four data voltages detected in a falling section of four effective pulses, in practice, numerous effective pulses need to be measured for comparison with the average number of effective pulses in a no-load state, and data voltages also need to be detected in each falling section of said measured effective pulses, and thus processing speed is degraded as the number of effective pulses is increased.